package com.hmdp.service.impl;

import cn.hutool.core.util.BooleanUtil;
import cn.hutool.core.util.StrUtil;
import cn.hutool.json.JSONObject;
import cn.hutool.json.JSONUtil;
import com.baomidou.mybatisplus.extension.plugins.pagination.Page;
import com.hmdp.dto.Result;
import com.hmdp.entity.RedisData;
import com.hmdp.entity.Shop;
import com.hmdp.mapper.ShopMapper;
import com.hmdp.service.IShopService;
import com.baomidou.mybatisplus.extension.service.impl.ServiceImpl;
import com.hmdp.utils.CacheClient;
import com.hmdp.utils.SystemConstants;
import org.springframework.data.geo.Distance;
import org.springframework.data.geo.GeoResult;
import org.springframework.data.geo.GeoResults;
import org.springframework.data.redis.connection.RedisGeoCommands;
import org.springframework.data.redis.core.StringRedisTemplate;
import org.springframework.data.redis.domain.geo.GeoReference;
import org.springframework.stereotype.Service;
import org.springframework.transaction.annotation.Transactional;

import javax.annotation.Resource;

import java.time.LocalDateTime;
import java.util.*;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;
import java.util.concurrent.TimeUnit;

import static com.hmdp.utils.RedisConstants.*;

/**
 * <p>
 *  服务实现类
 * </p>
 *
 * @author 虎哥
 * @since 2021-12-22
 */
@Service
public class ShopServiceImpl extends ServiceImpl<ShopMapper, Shop> implements IShopService {

    @Resource
    private StringRedisTemplate stringRedisTemplate;
    @Resource
    private CacheClient cacheClient;


    @Override
    public Result queryById(Long id) {
        //缓存穿透解决方案：
        // Shop shop = queryShopWithPassThrough(Long id)
        // 缓存工具类：Shop shop = cacheClient
        //                .queryWithPassThrough(CACHE_SHOP_KEY, id, Shop.class,
        //                this::getById, CACHE_SHOP_TTL, TimeUnit.MINUTES);
        //缓存击穿解决方案1，逻辑过期时间： Shop shop =  queryShopWithLogicalExpire(Long id)
        //缓存工具类：Shop shop = cacheClient
        //               .queryWithLogicalExpire(CACHE_SHOP_KEY, id, Shop.class,
        //        this::getById, CACHE_SHOP_TTL, TimeUnit.SECONDS);
        //缓存击穿解决方案2，互斥锁： Shop shop = queryShopWithMutex(Long id)
        //缓存工具类：Shop shop = cacheClient
        //                .queryWithMutex(CACHE_SHOP_KEY, id, Shop.class,
        //                this::getById, CACHE_SHOP_TTL, TimeUnit.MINUTES);

        //缓存穿透解决方案：
        Shop shop = cacheClient
                       .queryWithPassThrough(CACHE_SHOP_KEY, id, Shop.class,
                      this::getById, CACHE_SHOP_TTL, TimeUnit.MINUTES);
        if (shop == null){
            return Result.fail("店铺不存在");
        }
        return Result.ok(shop);
    }

    /**
     * 获得互斥锁
     * @param key
     * @return
     */
//    private boolean trylock(String key){
//        Boolean flag = stringRedisTemplate.opsForValue().setIfAbsent(key, "1", 10, TimeUnit.SECONDS);
//        return BooleanUtil.isTrue(flag);
//    }

    /**
     * 释放互斥锁
     * @param key
     */
//    private void unLock(String key){
//        stringRedisTemplate.delete(key);
//    }

    /**
     * 逻辑过期解决缓存击穿
     */
    /*开启线程池
    private static final ExecutorService CACHE_REBUILD_EXECUTOR = Executors.newFixedThreadPool(10);
    public Shop queryShopWithLogicalExpire(Long id){
        String key = CACHE_SHOP_KEY + id;
        //1.从redis中查询
        String shopJson = stringRedisTemplate.opsForValue().get(key);

        //2.判断redis是否命中
        if (StrUtil.isBlank(shopJson)){
            //3.未命中，直接返回
            return  null;
        }
       //4. redis命中,把shopJson反序列化为对象
        RedisData redisData = JSONUtil.toBean(shopJson, RedisData.class);
        Shop shop = JSONUtil.toBean((JSONObject) redisData.getData(), Shop.class);
        LocalDateTime expireTime = redisData.getExpireTime();

        //5. 判断是否过期
        if (expireTime.isAfter(LocalDateTime.now())){
            //5.1 未过期，返回店铺信息
            return shop;
        }
        //5.2 已过期，缓存重建
        //6.缓存重建
        //6.1获取互斥锁
        String lockKey = LOCK_SHOP_KEY + id;
        boolean isLock = trylock(lockKey);
        //6.2 获取锁成功，开启独立线程，实现缓存重建

        if (isLock){
            CACHE_REBUILD_EXECUTOR.submit(() -> {
                try {
                    //重建缓存
                    this.saveShopToRedis(id, 20L);
                } catch (Exception e) {
                    throw new RuntimeException(e);
                }finally {
                    //释放锁
                    unLock(lockKey);
                }
            });
        }
        //6.3 获取锁失败，返回过期的店铺信息
        return shop;
    }*/

    /**
     * 缓存击穿解决方案2：互斥锁解决缓存击穿
     * @param id
     * @return
     */
//    public Shop queryShopWithMutex(Long id){
//        String key = CACHE_SHOP_KEY + id;
//        //1.从redis中查询
//        String shopJson = stringRedisTemplate.opsForValue().get(key);
//
//        //2.判断是否存在
//        if (StrUtil.isNotBlank(shopJson)){
//            //3.存在，返回信息
//            return  JSONUtil.toBean(shopJson, Shop.class);
//        }
//        //3.redis不存在，判断是否为空值(缓存穿透空值)
//        if (shopJson != null){
//            return null;
//        }
//
//        //4.redis未命中,实现缓存重建
//        //4.1 尝试获取互斥锁
//        String lockKey = LOCK_SHOP_KEY + id;
//        Shop shop = null;
//        try {
//            boolean isLock = trylock(lockKey);
//            //4.2 判断是否获取成功
//            if (!isLock){
//                //4.3 获取锁失败-->休眠一段时间并重试
//                Thread.sleep(50);
//                return queryShopWithMutex(id);
//            }
//
//            //4.4 获取锁成功，查询mysql
//            shop = getById(id);
//
//            //模拟并发，重建缓存的延时
//            Thread.sleep(200);
//
//            //5.mysql不存在，返回错误
//            if (shop == null){
//                //5.1 避免缓存穿透，设置空值插入到redis中
//                stringRedisTemplate.opsForValue().set(key,"",CACHE_NULL_TTL, TimeUnit.MINUTES);
//                return null;
//            }
//            //6.mysql存在，转存到redis
//            stringRedisTemplate.opsForValue().set(key,JSONUtil.toJsonStr(shop),CACHE_SHOP_TTL, TimeUnit.MINUTES);
//        } catch (InterruptedException e) {
//            throw new RuntimeException(e);
//        }finally {
//            //7.释放互斥锁
//            unLock(lockKey);
//        }
//
//        //8.返回
//        return shop;
//    }


    /**
     * 缓存穿透解决方案：设置空值返回给redis
     * @param
     * @return
     */
/*    public Shop queryShopWithPassThrough(Long id){
        String key = CACHE_SHOP_KEY + id;
        //1.从redis中查询
        String shopJson = stringRedisTemplate.opsForValue().get(key);

        //2.判断是否存在
        if (StrUtil.isNotBlank(shopJson)){
            //3.存在，返回信息
            return  JSONUtil.toBean(shopJson, Shop.class);
        }
        //3.redis不存在，判断是否为空值
        if (shopJson != null){
            return null;
        }

        //4.不存在，查询mysql
        Shop shop = getById(id);

        //5.mysql不存在，返回错误
        if (shop == null){
            //5.1 避免缓存穿透，设置空值插入到redis中
            stringRedisTemplate.opsForValue().set(key,"",CACHE_NULL_TTL, TimeUnit.MINUTES);
            return null;
        }
        //6.mysql存在，转存到redis
        stringRedisTemplate.opsForValue().set(key,JSONUtil.toJsonStr(shop),CACHE_SHOP_TTL, TimeUnit.MINUTES);
        //7.返回
        return shop;
    }*/

/*    手动缓存预热(缓存重建)
    public void saveShopToRedis(Long id,Long expireSeconds) {
        //1.查询店铺数据
        Shop shop = getById(id);
        //2.封装逻辑过期时间
        RedisData redisData = new RedisData();
        redisData.setData(shop);
        redisData.setExpireTime(LocalDateTime.now().plusSeconds(expireSeconds));
        //3.写入redis
        stringRedisTemplate.opsForValue().set(CACHE_SHOP_KEY + id,JSONUtil.toJsonStr(redisData));
    }*/

    @Override
    @Transactional
    public Result update(Shop shop) {
        if (shop.getId() == null) return Result.fail("店铺id不能为空!");

        //1.修改数据库
            updateById(shop);
        //2.删除缓存
            stringRedisTemplate.delete(CACHE_SHOP_KEY + shop.getId());

        return Result.ok();
    }

    /**
     * 根据类型查询
     * @param typeId
     * @param current
     * @param x
     * @param y
     * @return
     */
    @Override
    public Result queryShopByType(Integer typeId, Integer current, Double x, Double y) {
        //1. 判断是否需要根据坐标查询
        if (x == null || y == null){
            //不需要坐标查询，按数据库查询
            Page<Shop> page = query()
                    .eq("type_id", typeId)
                    .page(new Page<>(current, SystemConstants.DEFAULT_PAGE_SIZE));
            // 返回数据
            return Result.ok(page.getRecords());
        }
        //2. 计算分页参数
        int from = (current - 1) * SystemConstants.DEFAULT_PAGE_SIZE;
        int end = current * SystemConstants.DEFAULT_PAGE_SIZE;

        //3. 查询redis、按照距离排序、分页。结果：shopId、distance
        String key = SHOP_GEO_KEY + typeId;
        GeoResults<RedisGeoCommands.GeoLocation<String>> results = stringRedisTemplate.opsForGeo()
                .search(
                        key,
                        GeoReference.fromCoordinate(x, y), //以当前用户经纬度坐标为圆心
                        new Distance(5000), // 查询半径5km
                        // 查询结果包含距离，限制为end(5)条
              RedisGeoCommands.GeoSearchCommandArgs.newGeoSearchArgs().includeDistance().limit(end)
                );
        // 4.解析出id
        if (results == null){
            // 无结果
            return Result.ok(Collections.emptyList());
        }

        List<GeoResult<RedisGeoCommands.GeoLocation<String>>> list = results.getContent();
        if (list.size() <= from){
            //没有下一页
            return Result.ok(Collections.emptyList());
        }
        // 4.1.截取 from ~ end的部分
        List<Long> ids = new ArrayList<>(list.size());
        Map<String, Distance> distanceMap = new HashMap<>(list.size());
        //stream流遍历，跳过查询过的前from个元素
        list.stream().skip(from).forEach(result -> {
            // 4.2.获取店铺id
            String shopIdStr = result.getContent().getName();
            ids.add(Long.valueOf(shopIdStr));
            // 4.3.获取距离
            Distance distance = result.getDistance();
            distanceMap.put(shopIdStr, distance);
        });

        // 5.根据id查询Shop
        String idStr = StrUtil.join(",", ids);
        //相当于 select * from tb_shop  WHERE id IN ( 5 , 1 ) ORDER BY FIELD(id, 5, 1)
        List<Shop> shops = query().in("id", ids).last("ORDER BY FIELD(id," + idStr + ")").list();
        for (Shop shop : shops) {
            shop.setDistance(distanceMap.get(shop.getId().toString()).getValue());
        }
        return Result.ok(shops);

    }
}
